Supervisory system



SUPERVISORY SYSTEM Filed Oct. 23, 1962 .Ts n@ m2 bw m.....+. s m l im@ mmm y M Q T m e n x E s N T 1 l t am u E o xnxx L( s 5 +I; fw, VNWIHH |L. a; ,QU H IIIIIIIIIIIIIIIIIIII IIL .TN Td J l WM. M 0V W n Oh um mn RW l mm R B mmfL. QN

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NN QN- V IIL United States Patent C) 3,231,878 SUPERVISORY SYSTEM Roger G. Kramer, Gardner,` and Chandler H. Waterman, Athol, Mass., assignors to lSinlpleiLTirne Recorder Co., Gardner, Mass., a corporation f Massachusetts Filed Oct. 23, 1962, Ser. No. 232,623

1 Claim. (Cl. 340-213) This invention relates to a supervisory system and more particularly to apparatus arranged to transmit indications of condition to a central station from a plurality of remote stations.

There are a number of fields in lwhich it is desirable'to have an indication at a central station of the condition of elements at various remote stations. Such an indication might, for instance, involve the lighting or nonlighting of lamps on a panel boardv in theycentral` station to show whether or not a certain condition exists at each of a plurality of positions some distance away. Such a condition may exist, for instance, in the case of a large plant in which it is desirable to know .duringV the` night whether certain lights are on or off. A` similar situation might exist in a machine shop in which a supervisor would like to know which machines` in the plant are operating at a given time. In a steam generating plant it might.' be desirable to know whether certain valves areopen or closed. A supervisory system of this type is'desirable because it makes it unnecessary for an employee to walk from one remote station to another to check the desired condition. Supervisory systems of this type which have been available in the past have sulfered from a number of deficiencies, however. For one thing, they have required a large number of wires; this factor has madel such systems very expensive, particularly where the remote stations have been a considerable distance from the central station. Furthermore, the known systems have been difiicult to maintain because of the complex electrical circuitry involved. In addition, they lack the ability to keep a permanent record of the length of time during a given day that any one of the `remote station subjects has 'been in a given condition. An example of such a desirable -information would be the total length of time that an intermittently-operated machine has been running. Also, one of the difficulties experienced `with the prior art supervisory systems is that a circuit difficulty in a remote station circuit may cause it falsely to indicate a certain condition and a considerable time may pass before `this false indication is discovered. These and other diiliculties experienced with the prior art devices have `been obviated in a novel manner by the present invitation It is, therefore, an outstanding object of the invention to provide a supervisory system which gi-ves positiv/estatus indication, which has a high ldegreeof accuracy, which is relatively `simple to construct, which Iis simple to install, which requires very little maintenance, and which is inexpensive.

Another object of this invention iis `the provision of a supervisory system in which only `two wires are required to connect a central station to a large number of remote stations, these wires being of very small gauge and being only two in number, irrespective of rthe number of lremote stations to be supervised.

Another object of this invention is the provision of a supervisory system having a means for checking the operability ofthe circuitry at the remote stations.

With these and other objects in view, as will be apparent to those skilled inthe art, the invention resides `in the combination of parts set forth in the specification and covered by the claims appended hereto.

The character of the invention, however, may be best understood by reference to certain of its structural forms `a rectifier circuit 43. A line 44 connects one side of the v'3,231,878 Patented Jan. 25, 1966 as best illustrated by the accompanying drawings in which:

The single figure is a schematic view of a supervisory system embodying the principles of the present invention.

Referring to the drawing, which shows both the general and' specific features of the invention, the supervisory system indicated generally by the reference numeral 10, is shown as consisting of a power supply 11, a central station 12, at least .one remote station 13, a test circuit 14, and van indicating circuit 20.

Power supply The power supply 11 is provided with a multiple lead plug 15 and it is provided with posts 1, 2, 3, 4, 5, 6, 7, and 8. The posts 1 and 2 are adapted to be connected to a source of 11115 volt 60 cycle A.C. electricity. The post 1 is connected by a line 16 through a fuse 17 to one side of a primary coil 18, the other side of which is connected by `a line 19 to the post 2 and also to the post 4. The coil 18 forms part of a transformer 21 having secondary coils: 22, 23,and 24. adapted to convert the 120 volt A.C. electricity to 15 volts in the case of coil 22, 20` volts. in the case of coil'23, and in the case of coil 24 into 60 volts which is` converted by a tapoi line to sections giving 40 volts and 20 volts. A rectifying network 25 is formed from four rectiiiers 26', 27, 28, and 29. One Aside of the coil 22 is connected to a line 31 t-o a common pointbetween the rectifiers 26 and 27, while the other side of the coil 22 is connected by a line 32 to a common point between the rectifiers 28 and 29. A line 33 is connected to the common point between the rectifers 26 and 29, while a line 34` is` connected to the common point between the rectiers 27 and 28. A 250 microfarad l5 volt capacitor 35 is connected between the lines 33 and 34 while a 50 o'hm 5 watt resistor 36 is connected lin the line 34 following the capacitor to form 4a filter. Across the lines 33 and '34 following the resistor 36 is a 1Nl524 Zener voltage regulating diode 37.

Four rectifiers 38, 39, 41 and 42 are connected to form `rectifiers 41 and 42. A 1600 microfarad l5 volt capacitor 48 isconnected between the lines 46 and 47. Also connected across the lines 46 and 47 are a 225 ohm 5 watt "resistor 49 and a 1Nl524 Zener voltage regulating diode 51 in series. The common point between the resistor 49 vand the diode 51 is connected by a line 52 to the bases of two 2N277 transistors 53 and 54. The collectors of both these transistors are connected to the line 47 and their emitters are connected to a line 5S which is connected through a fuse 56 to the post 6 of the plug 1.5. A ohm 1l0` watt resistor 57 is connected between the lines 46 and 47 adjacent the fuse 56 and the line 33 is also connected to the line 46 between the resistor 57 and the post 5 to which it is attached at its outer end.

One end of the coil 24 is connected to a post A, while the center tap is also connected to a post B. The other end of the coil 24 may be connected by a line S8 to a common point between two rectiiers 59 and 61 which form with two other rectiers 62 and 63 a rectifier circuit 64. A line 65 extends outwardly from the common point between the rectifier 62 and 63 and may be optionally connected to the post A or the post B. A line 66 extends from the common point between the rectifier 61 and 63, while a line 67 extends from the common point between the rectifiers 59 and 62. A 2() microfarad 100 volt capacitor 68 extends between the lines 66 and 67 and the line 66 is connected to the post 8 of the plug 15, while the line 67 is connected to the post 7. A line 69 is connected from the line 16 inboard of the fuse 17 to the post 3. An examination of the circuit will show, therefore, that in the plug 15 the post 1 is the 115 volt A.C. input. The post 2 is the 115 volt A.C. common. The post 3 is the 115 Volt A.C. output. The post 4 is the 115 volt A.C. common, also. The post 5 is the ground connection and has no voltage. The post 6 carries a minus l2 volt D.C. The post 7 carries a +12 volt D.C. and the post 8 carries +20, +40 or +60 volt D.C. depending upon the connection of the line 65 to the post A or B in conjunction with the connection of the line 58, either to the post A or B or the end of the coil 24.

Remote station A remote station 13 is connected by two lines 71 and 72 to the central station 12. These lines 71 and 72 may extend to other remote stations also. The remote station is provided with lines 73 and 74 which are connected to the local source of 115 volts A.C. electricity to serve the regulating motor 75. The line 73 is connected directly to the motor while the line 74, on the other hand, is connected to the motor through a normally closed switch 76 having an actuating finger in line to be engaged by a radially extending protrusion 77 on a cam 78 which is driven by the motor 75. Mounted across the normally closed switch 76 is a normally-open contact 79 of a relay 81, the relay having an energizing coil 82. The remote station is provided with a sensing relay 83 having a coil 84 which is connected to a status member 85 which is observing an element 86 whose condition it is desired to know at the central station. For the purpose of illustration, the element 86 is shown as an electric lamp, while the status member 85 is shown as a photoelectric cell which causes current to pass through the coil 84 when the lamp is not lit. The sensing relay 83 is provided with a normally closed contactor 87 which operates to be closed when the coil 84 is not energized; the coil 84 is not energized when the lamp is lit, so that the contactor 87 will remain closed as long as the lamp is lit. Now, one side of the contactor 87 is connected by a line 88 to one side of the normally-open switch 89. This switch has an actuating finger which is in line to be contacted by a protuberance 91 on a cam 92 which, also, is mounted with the cam 78 and driven by the motor 75. The other side of the switch 89 is connected by a line 93 to the line 71, the line 71 being connected through a polarity blocking diode 94 to one side of the coil 82 of the relay 81. The other side of the coil is connected to the line 72 and also is connected through a polarity blocking diode 95 to the other side of the normally closed contactor 87. An optional disconnect relay 96 is provided having a coil 97 and a normally closed contactor 98. The contactor can be connected in place of the line 88 if it is desired to have disconnect control over the remote station.

Central station The central station 12 is, of course, connected to the lines 71 and 72 extending to the remote stations 13. The central control 12 is also provided with a 1 r.p.m. motor 99 which is connected by lines 101 and 102 to the posts 4 and 3, respectively, of the plug 15. The drive shaft 103 of the motor has mounted thereon a cam 104 having a protuberance 105. Also mounted on the shaft 103 is a contact linger 106 which passes successively over contacts 107 equally spaced about the axis of the shaft 103, and generally equal in number to the largest number of remote stations, similar to station 13, which will be used. The central station contains a main switch 108 which has actuating finger in a position to be engaged by the protuberance 105 of the cam 104. The switch consists of four contact members 109, 111, 112, and 113. The

switch formed by the contactors 109 and 111 is normally open. The switch between the contactors 111 and 112 is normally closed and the switch between the contactors 112 and 113 is normally open. The engagement of the protuberance with the actuating fingers causes the normally closed switch between the contac tors 111 and 112 to open and the other two switches to close. The contactor 113 is connected by a line 114 to the line 72, while the contactor 111 is connected by a line 115 containing a series connector 100 ohm 1/2 watt resistor 116 to the line 71. A line 117 is connected to the plug 15 at either the post 7 or the post 8.

Indicating circuit The indicating circuit 20 is connected to the contact 107 by a line 118. The line 119 is connected at one end to the post 7 of the plug 15 and is connected through a line 121 to the indicating circuit 20. A line 122 is connected to the post 6 of the plug 15 and is connected by a line 123 into the indicating circuit 20. The indicating circuit is provided with a bistable element 124 consisting of a 2Nl966 transistor having a base lead 125, an emitter lead 126, and a collector lead 127. An incandescent lamp 128 is connected on one side to the collector lead 127 and on the other side to the line 123 which, because of its connection through the line 122 to the post 6, carries a minus 12 volts D.C. charge. The base lead is connected directly to the line 118 and is also connected through a 20,000 ohm 1/2 watt series resistor 129 to the line 121. This latter line, because of its connection through the line 119 to the post 7, carries a +12 volts D.C. charge. The emitter lead 126 is connected through a line 131 to the post 5 of the plug 15 and, therefore, is grounded. The bistable element 124 is a base-controlled four-layer semi-conductor of the type known as type 2Nl966 manufactured under the trademark DYNAQUAD by Tung-Sol Electric, Inc.,

Semi-Conductor Division, Newark, New Jersey. This element is a germanium alloy junction PNPN device that can be turned on and 01T by applying small control signals to its base. A negative pulse will turn the element on and it will remain on after the signal is removed. Turn ott' is accomplished by applying a positive pulse to the base or by dropping the collector current below the sustaining point.

Test circuit The test circuit 14 is provided with a line 132 which is attached to the line 114 and to the line 72. The other end of the line A132 is connected to a post 133 of a test switch 134 having a contact iinger which may contact the post 133 or may contact another post 135. The post 135 is connected by a line 136 to the line 122 carrying Ia minus 12 volt D.C. charge. The contact nger of the switch 134 is connected by a line 137 to a rectifier 138 which is arranged to pass current toward the line 137. The other side of the rectifier is connected to one end of a coil 139 of a relay '141, the other end of the coil 139 being connected by a line 142 to the line 117 and the contactor 109 of the main switch 108. The relay 141 is also provided with a movalble contact member 143 which v'is provided on either side with iixed contact members 144 and I145. It is the nature of the relay that when the coil 139 is not energized contact is made by the movable contact member 143 with the xed contact member 145. On the other hand, when the coil is energized, the movable member l143 moves over into contact with the contact member 144 only. The movable Contact member 143 is connected by a line 146 to the contact finger 106 of the central station 12. The fixed contact member 145 is connected by a line 147 through a 10,000 ohm 1A. Watt resistor 148 to the line 136 and the post 135. A .001 microfarad 400 volt capacitor 149 is connected between the test switch 134 central movable contact member and the side of resistor '148 adjacent the line 136. The ixed contact member 14.4 is connected by -a line 151 to the line 119 which, and therefore, carries a plus 12 voit D.C. charge.

v The operation of the invention will now be readily understood in view of the above description. There will, of course, be a number of indicating circuits 20 exactly corresponding to the number of remote stations 13. The condition of the incandescent lamp '128 indicates the condition of the element 86 in the remote station. The supervisory -system automatically reports the status of a considerable number of distant functions which are located at remote sensing stations 13. Each of the indicating circuits uses a bistable transistor having an indicating panel lamp 128 as its collector load. This `fourlayer (PNPN) transistor 124 will respond to a negative pulse to its base by turning on and remaining on despite the removal of the pulse. Fur-ther negative pulses will not aiectits state. However, the occurrence of a positive base pulse will result in its return to an oif condition extinguishing the iamp"128. All operations of the system occur through the single pair of telephone-type wires 71 and 72 through sequential scanning. Each complete cycle scanning consumes 1 minute, at the end of which the remote and central control circuits are antomatically synchronized. The sequence of events in a cycle ymay be described as follows:

Let the point of 0 reference time (00.00 second) be the instantv of synchronization at which time the polarity reversing switch or main switch 108 connects the line 71 to the lterminal 7 of the plug 15, this plug carrying a +12 volt D.C. charge. The main switch, at the same time, connects the line 72 to the post 6 of the plug 15 and to a -12 volt D.C. charge. The resulting 24 volt D.C. current which appears between these two wires being of the proper polarity (+12 volts D.C. on 71 and -12 Volts D C. on 72) passes through the rectifier 94 which is in the form of a blocking diode of each remote station 13. Approximately .002 volt A C. current passes through the coil 82 of the motor starting relay 81 thereby closing its normally open cont-actor 79. As the contactor 79 closes 1'15 volts A.C. electricity is supplied to the cam motor 75 (which has been stopped at tbe end of the previous scanning cycle by the ope-ning of its own motor-hold contact 76). The motor 75 is a 50 cycle 1 rpm. motor and all of these motors associatedi with the remote stations start rotating in unison and at 00.50 second they close their own motor-hold contacts because of the pnotuberance 77 of the cam. 78 leaving the actuating finger of the contactor 76, so that 115 volts A.C. electricity is supplied to each motor for the duration of the scan cycle. At 00.80 -second the polarity reversing switch or switch 108 disconnects the lines 71 and 72 from the posts 6 and 7, respectively, of the plug 15, thus deenergizing all relays 82 and then at approximately 00.85 second the main switch 108 connects the line 71 to the post 6, thereby effectively reversing the polarity on the two lines 71 and 72. The rectifier 94 then blocks this opposite polarity current from flowing through and picking up the Irelay 82. The relay 141 -is now in series with the 24 volt D.C. source and the lines 7'1 and 72. At 01.67 seconds all remote station motors 75 have carried their cams 92 with the protrusion 91 so that the protrusion contacts the contact 89 and closes it. However, since in a given supervisory system only one remote station has a circuit connection with the contact 107 in the central control 12 only that station will affect the lines 71 and 72. Hence, the central control 12 at this portion of the cycle will affect only one indicating circuit 20 corresponding to the particular remote station which is affecting the lines 71 a-nd 72. Now, if the sensing relay coil 84 is deenergizcd, indicating that the ele-ment 86 is in proper order, i.c., the light is on, then the norm-ally closed contact S7 of the relay 83 will remain closed. Since this contact 87 is in series with the status contact 89 across the lines 71 and 72, the

closing of both of these contacts will short the lines 71 and 72 completing the circuit involving the 24 volts D.C. electricity from the power supply and the relay 141. A-t 01.67 seconds then, the coil 139 will be ene-rgized and the relay 141 will be actuated so that the center con-tact 143 will engage the fixed contact 144. This has the effect of connecting the movable center contact 143 with the post 7 of the plug 15 and placing +12 volts D.C. on the contact 107 of the master scanner. Shortly after, at 02.20 seconds the master scanner selector contact 107 will make a connection to the line 118 running to the base lead 125 of the transistor 124 and cause` this y+12 volts D C. potential to appear on the transistor. If this transistor circuit is on, then it will be caused to tur-n oif by the presence ot this +12 volts D C. potential. If it is already olf, then it will remain so. The 'lamp 128 will be not glowing and, therefore, indicating to the personnel in the central station that all is proper at the -rernote station 13. The master scanner arm -or conact nger 106 continues rotating and at 02.50 seconds disconnects itself from the contact 107 of the indicating circuit 20. Several milliseconds later at 03.12 seconds the protuberance 91 moves off of the status contact switch 89 and opens it. At this time', then, the remove station 13 will have been scanned The panel lamp 128 associated with that remote station will be off and will indicate that the remotely located sensing relay 84 is deenergized indicating that the element 86 is in proper condition.

Continuing through the cycle at 03.33 seconds the scanning contact nger 106 will connect to the status contact corresponding to the switch 89 in the remote station 13. Again, since only one remote unit has any circuit connection to the number 2 status contact in the central control 12, only that remote station will affect the system at this point. Let us assume that the next remote station sensing relay is energized and, therefore, that its normally-closed contacts are open. At this time, then, the line 71 will remain disconnected from the line 72 and the selector relay switch 141will not be energized. The movable contact arm 143 remain connected to the -12 volts D.C. through the 10,000 ohm resistor 148 'and this -12 volts D.C. potential will appear on the contact. At 03.87 seconds the contact will be connected to the base of the indicating circuit transistor corresponding to the particular remote station in question and the -12 volts D C. will appear there. This circuit will turn on and the panel lamp will light. Cur* rent will ow from post 5 of the power supply terminal into the emitter -lead 126 of the transistor, through the transistor, through the lamp 128, and -back to the power supply terminal post 6. At 04.17 seconds the contractor 106 will move away from the line to the transistor. However, because of the bistable nature of the circuit, the lamp will remain lighted. At 04.78 seconds the scanner in the remote station will disconnect its protuberance 91 from the switch 89 and continue rotating. This progression through each contact successively will continue for the remainder of the 1 minute cycle. Each remote station will transmit its information regarding the energized or deenergized state of its sensing relay by way of a pulse or no-pulse return to the central control in the proper sequence. At 49.17 seconds the master scanner will disconnect from the las-t transistor base and at 49.78 seconds the last remote station will disconnect its status contact switch 89. A `few milliseconds later at 50.00 seconds the remote motor-'hold contacts 76 will open and all remote stations will have completed their cycles and their motors will stop. The motor 99 in the central station, thowever, is slower, being a 60 cycle 1 r.p.m. motor, and continues to rotate toward the start of the next cycle. During this interval of approximately 10 seconds any slight deviations which may have occurred between the master and the remote station motors will be automatically corrected. At 60.00 seconds, which will be 00.00 second of the next cycle, the |polarity reversing contacts in the main switch 108 will be closed in the central station. The remote motors will again be started and the whole sequence repeated. During this cycle, any changes in the status of the sensing relays 83 that have occurred since the previous scanning cycle will become reflected in the state of the panel lamps 128 at the central station 12.

The nature of the circuitry is such as to give specific lamp indications at the central station for certain abnormal or failure conditions at remote locations. The purpose of this is to incorporate a fail-safe quality in the system. A power failure at a remote station, for instance, will mean that the remote status contact switch 89 will not close at its appointed time; the selector relay 141 will not .pick up and the associated lamp circuit will turn on indicating, perhaps, an emergency condition lat that remote station. The purpose of the optional disconnect relay 96 is to forestall the possibility of a remote station shorting the lines 71 and 72 temporarily during a power failure should it stop while it is on its own status contact, or rather Iwhen the protuberance 91 -is in contact with the status switch 89.

The purpose of the test circuit 14 located at the central station is to provide a manual check of the central station components. When the movable contact of the test switch 134 is in the center, the selector relay 141 is temporarily disconnected from power and hence cannot pick up regardless of the condition of any of the remote sensing relays 83. Thus, as the master scanner arm or contact 106 rotates, it will sequentially place each lamp 128 on. 1f the movable arm of the switch 134 is placed in contact with the post 135 (its off position), the relay 141 will be constantly picked up or energized and the master scanner contact arm 106 will cause all of the fpanel lamp circuits to revert to off indication. When the test switch is again returned to contact with the post 133 (its run condition), then at the completion of the next cycle the master central station will again indicate true remote station status.

It is obvious that minor changes may be made in the form and construction of the invention without departing from the material spirit thereof. It is not, however, desired to confine the invention to the exact form herein shown and described, but it is desired to include all such as properly come within the scope claimed.

The invention having been thus described, what is claimed as new and desired to secure by Letters Patent, 1s:

A supervisory system, comprising (a) a master station including a scanner,

(b) `a plurality of remote stations, each having a status member including a means emitting a :positive and a means emitting a negative electrical pulse,

(c) a bistable indicators circuit with which the scarlner makes successive connection, the circuit being operable in response to a positive pulse to indicate a first condition at the remote station and being operable in response to a negative pulse to indicate a second condition,

(d) two wires only connecting the master station to all remote stations,

(e) means associated with each remote station yto connect the status switch of that remote station to the scanner only at the time that the scanner makes connection with the indicator circuit corresponding to that remote station, the indicator circuit remain- Iing in a state of indicating a rst condition despite receipt of the repetition of positive `pulse until the receipt of a negative pulse, the indicator circuit remaining in a state of indicating a second condition despite receipt of a repetition of a negative pulse until the receipt of a positive pulse.

References Cited by the Examiner UNITED STATES PATENTS 2,762,014 9/1956 Anderson 340-213 2,922,142 1/1960 Lappin 340-150 FOREIGN PATENTS 622,536 6/1961 canada.

NEIL C. READ, Primary Examiner. 

